The present invention relates to an electromagnetic fuel injection valve comprising a body fitted with a nozzle having at least one orifice communicating with an injection chamber supplied with pressurized fuel, and a metering valve controlled by an electromagnet.
On valves of the aforementioned type, the electromagnetic metering valve normally comprises a head having a control chamber, which is normally pressurized for closing the nozzle by means of a stopper. When the metering valve is opened, the pressure in the control chamber falls so as to move the stopper and open the nozzle.
Various injection valves of the aforementioned type are known, on one of which, the head of the metering valve comprises an appendix coaxial with the control chamber, and the injection valve body presents a passage for guiding the moving element of the injection valve, and which communicates with the control chamber via a conduit in the head. The injection valve body is formed in two parts connected to each other, and a red on the moving element is pushed into the closed position by a compression spring housed in a seat adjacent to the guide passage. The head also presents an axial appendix having an annular groove, which forms a receiving chamber communicating with the control chamber via a supply conduit.
The above injection valve presents several drawbacks. Firstly, the rod guide passage in the injection valve body requires accurate machining of the body. Secondly, the rod must be arrested inside the guide passage by a calibrated ring. Thirdly, difficulty is encountered in achieving effective pressure sealing of the fuel between the inlet chamber and the guide passage. Fourthly, the supply conduit remains wide open even when the metering valve is open, thus resulting in drainage of a large amount of fuel, which must subsequently be recovered. And last but not least, the lateral thrust produced by the spring results in frequent jamming of the rod.